The most frequent killer of Americans is coronary artery disease (CAD) and heart-related problems. The principal manifestations of CAD are coronary artherosclerosis (hardening of the coronary arteries) and stenosis (narrowing of the arteries), both of which ultimately force a reduction of flow to the coronary circulation (myocardial ischemia). An ischemic episode (either due to severe narrowing, or artery blockage) generally leads to angina pectoris, or a heart attack. During ischemia, various portions of heart muscle receive less oxygen which can ultimately lead to irreversible scarring and necrosis of the muscle tissue (myocardial infarction), reducing the efficiency with which the heart can pump blood to the rest of the body and possibly leading to fatal cardiac arrhythmias.
Recent research indicates that temperature monitoring and thermal pattern analysis of the cardiac tissue may provide more a precise qualitative and quantitative methodology to analyze the heart pathologies and functional status. Clinically, an electrophysiology (EP) catheter with a thermister at its tip is often used to monitor the myocardial tissue temperature for safety purposes during procedures such as atrial fibrillation ablation procedures. Although significant progress has been made in the electrophysiology analysis of cardiac arrhythmia, especially cardiac ischemia and infarction, there are several shortcomings with the current state of the art.
First, there are no non-invasive methods available for continuous temperature measuring, monitoring and mapping of the heart and circulation system. Thermister-based measurement using an EP catheter has limited measuring precision and accuracy, and also carries the potential risk of catheter position switching, as well as unreliable continuous measuring.
Second, current thermal scanning and monitoring techniques, such as using an intra-cardiac thermister, cannot provide the high resolution required for precise temperature measurement of cardiac tissue or for precise cardiac tissue localization. Further problems may include inaccurate operation procedure grasping and time synchronization (i.e., the simultaneous conformity of heart rate and blood flow in a patient's heart) and myocardial infarction (MI) emerging and recovering, which relate to the development of a potential myocardial infarction (a heart attack) and the uncertainty of when a heart attack may be about to occur, or whether the heart will be able to heal from a heart attack or will be irreparably damaged.
Third, current cardiac tissue temperature monitoring using a catheter/thermister is typically focused on single point/position. As a result, it cannot provide real time 2D and 3D continuous thermal mapping and scanning of cardiac tissue.
Fourth, there are no methods currently available for electrophysiological function analysis correlated heart tissue thermal monitoring and diagnosis.
Fifth, there are no multi-dimensional temperature and thermal pattern analyses for ischemia recognition and diagnosis, for example pecutaneous transluminal coronary angioplasty (PTCA) procedure monitoring, or long term monitoring of the growth of myocardial ischemia and infarction of heart tissue, ischemic/infarcted size, pathological tissue border, volume and pathology/healthy index analysis.
Thus, there is a need for a temperature scanning and pattern analysis-based method for cardiac tissue monitoring for clinical applications, since cardiac tissue thermal analysis and mapping is correlated to blood flow in the cardiac chambers and tissues. Further determinations may be made using such a method, including blood flow speed, volume per heart beat, and the like, especially for the left ventricle.